Need advice - "Blinker" (Hazard) Control Unit early 901

[SAM1]

Dear 911´s,

Actually I discovered a problem with my Hazard-Light-Control-Unit.

My car is a ´65 and the control unit is located behind the drivers side floorboard - together with two relays.......

The part I am talking about looks like a silver alloy can with 4 connectors........

It was manufactured 10/65, the part number is 90161534110.

The connectors are: *30* / *S* / *R*/ *L*.............

So.....most (all) of my connections are well connected to ground (gain) an Lights, Horn(s), indicators work fine and bright.......

Just this little control unit only worked eventually - it often depends on the position of the unit.......

While this part number is no longer available by porsche im am looking for some advice - on how to test this unit ........

I opened the can - and on the insight it is like a two way relay with a heated bimetal switch......

So what kind of setup can I build to check the unit.......

If I pull the hazard switch (big one - above the radio) the unit clicks - but nothing else so far.....?!

I will post some pics tonight......thanks for the support !

wbr

SAM

[SAM1]

Partnumber 901 615 341 10



SBG (LOGO) 35 / 12V 4x32cp / 90161534110 / 10-65



Open "CAN"









The following wires are connected:

S-Pin red/white
30-Pin green/white
R-Pin green/black
L-Pin 2 x black/white

The following values can be measured (to ground):

Hazard switch -OFF- :
red/white 12V
green/white 12V
green/black 0V
black/white 0V

Hazard switch -ON- :
red/white 12V
green/white 12V
green/black 0V
black/white 0V

Indicator switch RIGHT/On- :
red/white 12V
green/white 12V
green/black 0V
black/white 0-12-0-12.... V trigger

Indicator switch LEFT/On- :
red/white 12V
green/white 12V
green/black 0-12-0-12.... V trigger
black/white 0V

So what ?

I am confused what the switch does ?

It worked well before - any tips ?

Thanks!!!
SAM

[304065]

Well, I'm going to tackle this also.

Now, the can is NLA. However, there HAS to be something that works, even if its a modern electonic piece, which doesn't bother me in the slightest, as the can (AND a couple of relays) are hidden behind the pedal board. The only visible relays are the blinker (stay tuned) and another mysterious relay, that I think is the lowbeam/higbeam "changeover" located on the drivers side, just forward of the fuel gauge.




Another picture of the can. A big shout-out to the prior owner who painted it, and all the wires, with brown underseal. May he be confined to a special circle of hell.

[304065]

Can anyone tell me definitively which the left and right relays are?

[304065]

"30" is DIN nomenclature for "positive direct output from battery." Comes off battery side of fuse #4, goes through a fuse, then to relay contact #86 on the "control light relay" or hazard relay- then to terminal 30. So this is "hot" all the time.

L and R are the leads to the left-side and right-side signals, respectively.

S is a switched ground, from the switch. When the switch is puled out, terminal 2 of the switch, the ground, makes contact with terminal 1, which grounds terminal #85 on the control light relay. This actuates the relay, which DISCONNECTS power from the blinker relay (#44 in diagram). It also grounds terminal S on the hazard blinker, completing its circuit and causing it to blink- 0, 12v, 0, 12v as the bimetal strip bends back and forth inside the can. Finally, 12v is picked off the L terminal which is routed back to the switch, which lights the bulb (the red lamp on the switch).

[304065]

Ok, and the circuit logic for the turn signals. . .

The blinker is a thermal type with a bimetallic strip- it heats up and opens, then cools down and closes, providing a pulsed =12v. The "C" terminal conforms to DIN 72552, it's the "Pilot" or indicator contact- and the others are 49 and 49A, the "input" and output" from the turn signal flasher.

The "input" power to terminal 49 comes from the normally closed contact on the control light relay (the hazard relay).

So basically, when you throw the turn signal switch left or right, you complete the path to ground-- from battery through control light relay to input to output to turn signal switch through turn signal switch to wye connector, one branch of which is to the bulb and to ground. The other branch of the wye is connected to the hazard flasher-- it's what allows the hazard flasher to power the turn signal switch when the blinker is disconnected.

When you pull the hazard switch on, it energizes the hazard relay- which flips the wiper over to the NO contact- and OPENS the NC 87a contact- which removes power from the blinker input.

[304065]

912 guys are great.

http://www.hillmanimages.com/912/ts_blinker.html

[304065]

By the way, the can was made by Stribel (AFL Stribel GMBH).

[304065]

OK, I've got workaround figured out with modern parts.

One of the goals was to design something that could be easily repaired/replaced in the field. I was originally considering, for example, a Bosch DPST headlamp relay, like that found on an old BMW motorcycle. However, those are somewhat rare, and about 10x the price of a $1.79 40A Bosch SPDT relay.

So here's the plan.



The original SWB switch works by grounding the can- power flows from 30 through the thermal flasher to ground. In the ground position, a relay wiper is also pulled into contact, which is a double pole (you must have isolation between both poles of the wiper, otherwise both turn signals will flash when you only apply one). The thermal element heats up and breaks the contact. Mechanically, the thermal wiper moves back into the closed position and it starts all over again.

Now, the modern fix uses a pair of Bosch SPDT relays (terminal 87a omitted for clarity) and a Tridon EL13 Electro-mechanical flasher unit. When the switch is pulled, terminal S is grounded, which allows current to flow through the flasher unit to terminal 86, which energizes both relay coils, allowing current to flow from terminal 30 into the turn signals. When the flasher unit breaks the contact, the coils are de-energized and the current flow stops.

The reason for using two relays is that you must have both left and right signal circuits isolated when off. Rather than use a DPST or a bigger DPDT (like a Hella or the rebadged MSD) I chose the cheap, redundant route-- Bosch icecube relays are plentiful and can be had at most parts stores.

Also, everything should be small enough to fit in a metal box or can similar to the size of the original unit. I suppose if I really wanted to go crazy, I could fit everything inside the original can, but that would require different components.

Any thoughts?

[304065]

Well, the above didn't work.

Here's what did.



The circuit logic of the earlier workaround was flawed: the current flowing through the relay coils was not enough to get the flasher unit to work, even though it is a variable-load type.

This second iteration was an attempt to put two 32cp lights and the associated wiring in the "L" or load circuit of the flasher- that would certainly get it to operate. I had originally considered using two flashers in the 87 terminal outputs from the relays, and tried it, but ended up with different flashing rates-- it looked like a circus car. So then it hit me, I could drive the second relay's coil input with a multiple from the flasher's output, and run them simultaneousy, while retaining electrical isolation between the individual turn signal circuits.

Remember, the reason to do this rather than just hooking both turn signal circuits to the "L" output of a flasher is that if you did that, you would get both turn signals operating when you just wanted one. The factory can had a DPST relay inside, along with a thermal flasher-- small and effective. In later years, they went to a grounded, electromechanical type that ran both turn signals and hazard, and the changeover was in the hazard switch.

I also took the opportunity to FIX a major error that some PO had done, and all subsequent PO's missed-- the front turn signals were wired to the bulbs for the parking lights. So rather than a big 32cp lamp at the corner of the car flashing, a wimpy 2cp bulb in the small square next to the horn grill signaled your intention to turn. Not very smart in today's modern traffic.

Anyway, it's done. . . not easy to reverse-engineer the Germans of 40 years ago. Attached are pictures. With apologies to those who would have demanded the DIN spec for the wire colors, these were the sockets I had!

[304065]

[911K]

John,

Do you think the attached picture of a BMW 2002 relay might work without the added relays?

My '68 911 has a bad turn signal relay and I'm just looking at options.

Thanks,

Mike

[304065]

Mike, that 2002 relay would probably work in the 69- LWB cars, but I doubt it would function correctly in an SWB. Plus it's about $45.

As you can see on the side of the can, the terminals are 31 (ground) 49a and 49 (input and output) and C (pilot lamp). This suggests that two wires is used to turn the unit on, one to light the pilot lamp, and the remaining single terminal to power the signals. There are tons of domestic flasher units that do the same thing, but the problem with that is, once you make an electrical connection between the two sides of the car (left bulbs and right bulbs) so you can flash them with a single contact, you end up lighting all four bulbs when you only want to light two (when you throw the turn signal stalk).

[911K]

John,

I just made up this relay conversion for my car this morning as the original flasher unit would only work on the left side circuit.

I just finished up and put everything back together and noticed in your legend that I hooked up the left circuit wire wrong, but the hazards now work. Instead of wiring the left wire to the "P" on the flasher unit along with the "86" wires from the relay, I connected it to the "L" terminal on the flasher unit as that's what I thought the drawing was indicating. I came back in and looked at the actual photos of your installation and saw that the "L" wire is supposed to be hooked up to the "P" terminal.

Is this going to cause a problem even though all four of the lights are flashing? I did notice that when I turn the flasher switch off that the turn indicator lights in the speedometer flash one time. Does your car do this?

Since it's no big deal to go back and connect the left side wiring up to the "P" circuit, I will if you think it's a good idea.

Let me know what you think.

Thanks,

Mike

[304065]

Mike,

Great! I am very pleased that the diagram was helpful to you.

I don't think connecting it to either "power" or "load" matters if the circuit works, the other one is a no-connect. You could even use a two prong flasher, all you need is something that mimics the action of the original relay wire heating up and breaking the circuit, then reconnecting when it cools down again.

I think I get the single flash when turning it on or off also, I think it's feedback into the "c" circuit from the signal flasher, but I'll check next time I am with the car. I have some work to do in that area as when I turn on the left or right signal I get BOTH indicator arrows.

How about a picture of your setup? Would make my day.

JFC

[911K]

John,

Actually what I did was hook up the black/white left turn signal feed wire from the wiring harness to the "L" terminal on the flasher unit as I read your diagram wrong. However, the hazards and turn signals work correctly so you might want to hook up your wiring like this and see if your turn signal indicators flash correctly.

I just used two 30 amp relays and an EL13 flasher that I had in the garage along with some electrical tape to hold everything together to see if it would work, so I don't have any pictures to post.

I've got the same relay holders that you used at work that I'll wire up and install and will post pictures after I've got the permanent set-up.

Thanks again for this post. I defintely could never have figured this out on my own!

Best regards,

Mike

[Nick912]

Thanks to John for referring me to this thread, I will have to examine my underdash setup, but in the meantime, could anyone help me identify the rectangular five terminal flasher unit I found in the front of the car wired up next to the battery? Initially I got power off one off the leads and one that oscillated between some power and open field so I thought that had to be the turn signal flasher unit, but I'm not getting anything on it anymore, and I can't figure out the wire arrangment on the new-to-me flasher unit I got from foreign intrigue in Maine.

Could I be barking up the wrong flasher here?


many thanks,

Nick

[911K]

Nick,

My '68 911 doesn't have a five terminal flasher by the battery. There is a horn relay right by the washer pump that might have five terminals IIRC.

My turn signal relay has three terminals and is located just to the left and above the fuse block. It should be in the same location for your car.

Mike

[304065]

There is no five terminal flasher in the wiring diagram, it must be aftermarket. What does it say on the flasher?

What do the terminals say on the flasher from foreign intrigue? What does it look like.

[Nick912]

I've included a couple of photos, the markings on the side read "30/51 12 Volt"

The terminal labels (reading clockwise starting at the stand alone terminal) are:
87, 30/51 (the two middle terminals are connected), 85, 86.

Is this my turn signal flasher? What is it if not, and where should I be looking in my '67 912 to make my turn signals blink, ye olde arm signals are getting tiresome.


Thanks!

Nick